Hot runner nozzles are generally known. They are used in injection molds for feeding a flowable plastic material at a predefined temperature under high pressure to a separable mold block (cavity). In order that the usually hot compound would not cool down prematurely within the nozzle, one known type of system employs an electric heater that concentrically encloses a material pipe and a flow channel formed therein to hold the liquid plastic material at a constant temperature down to the nozzle tip, if possible. A disadvantage with this type of system is that the heater which concentrically encloses the material pipe takes relatively much room so that the nozzles cannot be arranged side by side as closely as perhaps desired. Many applications, however, require that the spaces between the cavities might be filled simultaneously or more complicated components might be filled by several shots at short distances.
To overcome this disadvantage, DE-U1-296 10 268 suggests to arrange the nozzle channel and the heater side by side in a common casing. Parallel to the straight nozzle runner, the casing is provided with a bore for receiving the heating unit designed as a rod-shaped heater that almost reaches to the nozzle tip.
Also, due to the arrangement of nozzle duct and heater next to one another, hot runner nozzles of the afore-mentioned type, contrary to conventional nozzles where the heater is arranged so as to be concentric to the nozzle duct, are useful in particularly narrow environments which enables the use of this type of hot runner nozzle for injection molding tools having mold cavities, that are arranged so as to be located next to one another in a particularly narrow manner. However, depending on the given mounting or particular attachment methods, a more or less distinct lateral displacement of the hot runner nozzle can take place in response to the thermal expansion behavior of the hot runner nozzles due to the lateral arrangement of the heater to the nozzle duct, as opposed to a concentric arrangement.